1. Field of the Invention
The present invention is an improvement on U.S. Pat. No. 7,697,709 and relates to an earphone for use with audio systems and communication systems and more particularly to an earphone with multiple speakers (sound drivers) structured in a front-and-back straight arrangement at the same axis line or different axes lines, or structured in a front-and-back angled arrangement, to achieve three-dimensional stereo sound effects with bass/middle/high frequencies of sound and to achieve three-dimensional direction-adjustable stereo sound for hearing safety and wearing comfort.
2. The Prior Art
There are more and more types of earphones coming into the market, especially for many multi-functional MP3 players, MP4 players, and cell phones such as, Apple's iPod®, iPhone®, iPad®, etc. A big challenging issue in front of earphone developers and makers is that earphone size is demanded to become smaller and smaller and more focused on an In-Ear style for convenient and comfortable wearing, and at the same time, earphone sound quality is demanded to become higher and higher to match a full-scale sound in bass (low), middle, and high frequencies, and further, a real-stage-like 3D stereo sound space and effect. One speaker at a certain small size has not enough sound power to achieve full-scale sound quality. So-called stereo sound for small earphones, especially In-Ear earphones, only has a two-dimensional (X-Y) sound range, i.e. 2D sound with bass/middle/high frequencies. The three sound frequencies of bass/middle/high are only for different sound volumes and contents. In that case, the so-called stereo sound is for three frequencies of sound only, not for a real stereo sound, i.e. not for a three-dimensional (3D) sound space or effect. Due to the space limit, there is no third dimensional (Z) depth sound with those small earphones. Therefore, those small earphones are not able to achieve X-Y-Z three-dimensional stereo sound space/effect with bass/middle/high frequencies of sound. Of course, if there is a big earphone or headphone having a big space, multiple speakers can be put anywhere to have a fully arranged sound quality. Obviously, the dilemma is not only how to put more multiple speakers (multiple sound drivers) into a small earphone having a very limited size, but also how to arrange those multiple speakers for better 3D stereo sound effects.
As prior art, there are many types of small earphones having multiple speakers, i.e. multiple sound drivers, in the market already. The arrangements and structures of those multiple speakers still follow the traditional speaker arrangement: a parallel horizontal arrangement. The reason for arranging the speakers in a parallel horizontal arrangement is that a traditional sound study and research system needs to set all sound sources to be working at the same parallel level point within a certain sound environment, especially for one small earphone container containing multiple sound sources, i.e. multiple sound drivers. Even with those multiple sound drivers, the three sound frequencies of bass/middle/high are only for different sound volumes and contents, maybe in X-Y two-dimensional sound space.
The problem of those multiple speakers in the parallel position is that they are not able to develop a real stereo sound, especially for bass (low) frequency in a deep sense, because the area of the multiple parallel speakers is too small to have a good resonance depth space and effect. Those small earphones with multiple speakers are still only with a sound range in the X-Y axes - - - 2D sound with bass/middle/high frequencies, and not for a real stereo sound of 3D sound space or effect.
Apple In-Ear Headphones with Remote and Microphone have two drivers on each earpiece, one driver as a woofer and another one as a tweeter. Those two drivers are arranged parallel to one another for rich and detailed sound reproduction and bass response. Because the two sound drivers are arranged in parallel in a very small space, the bass response is not strong and is not rich enough and lacks deep sound space and effect in a third dimension (Z).
Shure provides two kinds of In-Ear earphones with multiple sound drivers, one with dual sound drivers and another one with triple sound drivers. Dual High-Definition Microdrivers for the item number SE425 are a tweeter and woofer for accurate and balanced sound in parallel structure. Triple High-Definition Microdrivers for the item number SE535 are one sound driver as a tweeter and dual sound drivers as woofers arranged in a parallel structure for spacious sound and rich bass. As for the other known earphones having multiple speakers, because the dual or triple drivers are arranged in parallel in a very small space, the bass response is not strong, is not rich enough, and lacks deep sound space and effect in a third dimension (Z).
M-Audio has a very famous In-Ear earphone, IE-40 acclaimed Ultimate Ears Technology, with three separate high-definition precision-balanced armature drivers for high, mid and low frequencies of sound. Ultimate Ears Technology is with a patented Dual-Bore Design to send a wider sound through separate acoustic canals for high and low channels, which allows the sound to be directly sent and mixed naturally in a user's ear. In other words, the Dual-Bore Design mixes all frequencies in a user's ear through a high frequency canal and a mid-bass canal into a user's ear, but does not mix all frequencies inside the earphone before delivering them into a user's ear. The dual drivers or triple drivers are arranged in a parallel structure. Also, the high and low canals are arranged in a parallel structure. Obviously, the bass response of IE-40 is not strong and is not rich enough because there is no resonance area inside IE-40 for bass deep response. Ultimate Ears of Logitich uses the same technology for its various earphones with multiple drivers.
There are two U.S. patent applications related to dual-frequency coaxial earphones: U.S. Patent Application No. 2009/0279729 A1 and U.S. Patent Application Publication No. 2010/0046783 A1. Those two applications discuss a shared magnet to work with dual frequency voice coils, one for low-frequency and another one for high-frequency. Those voice coils of low and high frequency speakers shared coaxially with one center magnet are not able to be independently and separately arranged or structured for stereo sound outputs. There is no deep space with those dual-frequency coaxial earphones.
An In-Ear earphone is a very particular earphone design that requires a special closed/isolated sound environment from the sound sources, to the sound effect area and resonance area, and to the output unit into a user's ear tunnels directly and closely as much as possible. There are three basic considerations for In-Ear earphones: small size, real stereo sound quality with bass/middle/high sound frequencies, and wearing/hearing comfort into a user's ear tunnels. Those considerations have to be achieved within a very small, closed, and isolated sound space and output environment and structure, which usually is an ear cup/shell and an In-Ear mushroom head.
Through studying the above five kinds of earphone products, there are many problems and issues still needed to be solved. The first problem or issue is that when the In-Ear earphones are built smaller and smaller, the sound is highly demanded to have a real stereo sound quality in three dimensions (X-Y-Z). Within the very limited small space, the In Ear earphone needs a better structure, better sound system, better arrangement of multiple speakers and related resonance sound effect area for high quality X-Y-Z dimensional 3D sound achievement. The conventional stereo sound in two dimensions (X-Y) is not enough to satisfy people's needs, and actually is not a real stereo. All of the above five kinds of earphones have no third-dimensional depth sound quality (Z axis) because of their parallelized structures - - - no X-Y-Z 3D stereo sound space and effect.
The second problem is that all old and current earphones, including the above five kinds of earphones, are preset for sound direction and channel stereo effects and usually focus on the back head center point of the earphone user. When an earphone user uses the earphone too long, his back center point of hearing nerve may be damaged.
The third problem is that the sound effects and sound output directions are always separate in all earphone products, especially for In-Ear earphones. People need a new product with hearing safety and sound high quality worked together at the same time for life enjoyment including music and health.
Generally speaking, with known earphones there is no way to have the earphone sound quality with X-Y-Z 3D stereo sound effects and 3D sound directions. Those earphones including the above five kinds of earphones have so-called stereo sound effects with no third-dimensional (Z) depth sound quality and/or have sound direction with no third dimensional (Z) depth adjustment.
Therefore, in order to solve the foregoing problems and drawbacks, a need exists for an earphone, especially for an In-Ear earphone, that has 3D stereo sound effects and outputs in X-Y-Z three dimensions, just like real-stage sound effects. Another need exists for an earphone, especially for an In-Ear earphone, that has 3D sound direction adjustments in X-Y-Z three dimensions for hearing safety. A third need exists for an earphone, especially for an In-Ear earphone, that has 3D stereo sound effects and 3D sound directions working together simultaneously and synchronously to achieve the highest sound quality in 3D stereo space inside small earphone pieces, to minimize hearing damage and loss to an earphone user, and to maximize the 3D stereo sound instantaneous real time effect experienced by the earphone user.